Since vermiculite emits far infrared light which is beneficial to the human body, and has excellent deodorization effect, antibacterial effect, and fire resistance, it is widely used in materials for construction, ceilings of motorcars and trains, wall materials, electronic materials, and the like and is added in powder form to nonflammable paints, coatings, fillers, and the like.
In particular, vermiculite has a characteristic of expanding when it is fired at high temperature. Since such expanded vermiculite has low density and exhibits excellent deodorization effect, antibacterial effect, and fire resistance, it can be manufactured into a board (plate) shape and is being used as an interior or exterior material for construction.
Although vermiculite has various advantages, particle sizes thereof are not uniform, and it is a mineral having many pores with non-uniform sizes and very high deformation. Accordingly, vermiculite has no adhesive force (cohesive force), thereby being manufactured into a vermiculite board using a binder.
Korean Patent No. 10-0695910 (registered on Mar. 20, 2007) discloses a vermiculite board including 100 parts by weight of expanded vermiculite, 50 to 90 parts by weight of an organic binder which includes 70 to 90% by weight of an epoxy resin and 10 to 30% by weight of a phenolic resin, and 1 to 10 parts by weight of clay.
Although the vermiculite board has high strength, the organic binder generates severe exhaust (toxic gas) when it is burned.
Korean Patent No. 10-0760149 (Sep. 18, 2007) discloses an interior material for construction manufactured by mixing and stirring formed stone, which is produced by foam-molding vermiculite, with sodium silicate, and then compression-molding and drying the same.
Although the constructional interior material has excellent flammability, sodium silicate, as a binder, has poor flowability. Accordingly, it is difficult to accomplish uniform mixing, whereby the mixture is partially agglomerated and becomes lumpy. In addition, since the mixture is very sticky, it is difficult to feed the same into a mold in a predetermined amount and, accordingly, it takes long time to produce the constructional interior material.